Biggest Solar Flare in Years—Auroras to Be Widespread Tonight?
Explosive magnetic reconnection aims "firehose" of charged gas at Earth.
(Video: Solar Flare Causes "Sunquakes.")
The most powerful explosions in the solar system, solar flares occur when magnetic field lines on the sun cross, cancel each other out, then reconnect.
These "explosive reconnections" release huge amounts energy as heat—in this case, a short blast measuring roughly 35 million degrees Fahrenheit (19 million degrees Celsius), according to physicist Dean Pesnell, project scientist for NASA's Solar Dynamics Observatory, or SDO.
In visible light, only the small dark surface blotches of sunspot 1158, which spawned the flare, could be seen. Without the SDO satellite, "you would never have known what was happening above" the sunspot, Pesnell said.
But the satellite's ability to detect many wavelengths of light allowed the observatory to image not only
